Mark Ritter knows he'll never get rid of all the rats in St. Louis -- but as long as he gets the ones he's after, that's all right with him

Mark Ritter pulls his white city pickup truck to the side of the road and points up the sloping hill of Melvin Avenue, in the far north spur of St. Louis. Small houses, some of them neatly kept, others in shambling disrepair, line the streets of this poor and working-class neighborhood just a few blocks from the Mississippi River.

During heavy rains, Ritter says, runoff from the city's antiquated sewer system drains down the hill and creates a prime breeding ground for rats at the bottom. "I know the sewer system here is contributing to the problem," he says.

The white wood-frame house Ritter has parked in front of has had a rat outbreak. Crews from the vector control division of the St. Louis Department of Health have been out a couple of times to lay poison pellets, but effective rat control usually takes six to eight weeks. That's long enough to tax the patience of any resident who's seen a rat.

Ryan Greis

Jennifer Silverberg

Mark Ritter, head rat man for the St. Louis Department of Health, spends most of his days chasing down vermin. After twenty years in the extermination business, hes learned how to think like a rat  and he knows as much about them as anyone in the city.

Jennifer Silverberg

Pest control worker Anthony Elliott accompanying Ritter on an expedition into the heart of local rat habitat

Jennifer Silverberg

The more rats Ritter can put in this state, the happier he is.

Ryan Greis

On stressful days, I can just gather my guys and tell them, Go forth and kill.

Ryan Greis

There are a lot of people who have no idea whats underneath their bird feeder at night.

Ryan Greis

Ritter often finds himself trying to think like a rat: Its easy for me. Im a bureaucrat.

Ritter, vector-control supervisor for the city of St. Louis, scans the front yard and quickly spots a small hole, about six inches across, nestled in the corner of the yard between the house and the driveway. It probably leads to a burrow under the concrete front porch, and it could house as many as a dozen brown rats. The grass around the opening has been chewed away, indicating that the rats that dug the burrow are still using it.

"Rats don't like to be touched, so they clear all that away at the entrance," Ritter says. He's 46 years old, rotund and congenial, but his round, open face and glasses make him look younger. He wears a baseball cap, even on the few days a year when he has to wear a necktie. A regular guy who's been reined in by a management position, he relishes the few opportunities he gets to be, as he says, "out in the field." And he knows as much about rats as anyone else in the city.

As he's examining the hole, a woman opens the front door and sticks her head out, curious about the strangers in her front yard at 9 a.m. on a brisk day in late March.

"We're with the health department," Ritter says, waving his hand toward her before she has a chance to say anything. His eyes stay focused on the hole. "It's OK."

The woman says she hasn't seen rats in the past few days and asks Ritter whether they're gone. He tells her they're probably still living under the house but that his crew will be back soon. He reminds her to keep her garbage cans tightly closed. She nods.

"As long as they don't come in here, that's all right," she says.

No one knows how many rats live in St. Louis. Just as people exaggerate the size of the rats they see scurrying along downtown streets or alleys, they tend to overestimate the number of rats on the basis of anecdotal evidence. In the 1970s, when rats were a huge problem in New York City and all along the East Coast, experts guessed that the rat population of the United States might equal the human population.

Most rat experts tend to dismiss those figures now, saying there's no way to count rats anywhere. Rats are nocturnal, and they carefully avoid people and predators. The most common species in most big cities -- the Norway rat, or Rattus norvegicus -- lives primarily underground, so an exact count is next to impossible. Even Ritter says he's only seen live rats seven times in the nine years he's been with the city's vector-control office.

But for people who've encountered rats -- who have seen them corner a pit bull or watched dozens of them feast at a grain silo or met them in their own toilets -- the experience can be haunting.

See a rat, and you'll never forget it.

It's not necessarily size that makes an impression. An average adult rat reaches ten inches in length, not counting a seven- to eight-inch tail, and tips the scales at a pound or so. At its biggest, a rat is much smaller than a typical pet dog or cat, but what a rat lacks in size, it more than makes up for in attitude.

A rat, for instance, will hold its breath for five minutes and swim a mile and a half just to reach your bathroom. Like Spider-Man, a rat will crawl straight up the side of a brick building; like Superman, it can jump from a 60-foot-tall building and land on its feet. If cornered, a rat will attack cats, dogs and even human beings. Not unlike a typical fraternity member, a rat maintains a single-minded focus on life's basics -- food and sex.

A rat can find food almost anywhere. Rats are omnivorous and will even resort to cannibalism when food is scarce, with the stronger males killing and eating the weaker ones. They prefer grains and cereal but will eat fruit and nuts, dog food, garbage or even animal waste, and they ruin far more food than they actually consume. For shelter, Norway rats like to be close to the ground -- or underground, if they can. They dig under houses, make burrows in basements or inside building foundations, or settle under abandoned cars and outdoor woodpiles.

Bigger, stronger rats dominate the best food sources, forcing weaker rats to forage in the daytime. Rats will travel about 150 feet from their burrows to gather food, but they follow established trails, usually hugging walls and staying out of sight. The oil on their coats leaves a greasy, smelly smudge that other rats follow.

A male usually lives with two or three females. Their lifespan is about a year and a half, but they reproduce rapidly. They reach sexual maturity at eight to twelve weeks and produce five or six litters a year, with seven to ten pups in each litter.

Ritter, who's spent much of his life learning to think like a rat, sums it up this way: "Rats eat and reproduce. That's about all they do."

Ritter has been chasing rats, in some capacity, for nearly twenty years. He ran the custodial department at Maryville University, helping with landscape maintenance and groundskeeping in the 1980s, then worked for a private extermination company for a year in the early '90s. He joined the vector-control division in 1994 and worked there for a couple of years, then for two years as a city lead inspector, before becoming vector-control supervisor in 1999.

"It can be tough on a person," says Rich Stevson, head of the health department's animal-control and vector-control divisions, "especially in the summertime, during mosquito season, and especially after the summer we had last year with the West Nile virus. He has no free time. I'm constantly throwing things at him, and he's always out in the evenings, giving talks and presentations."

Ritter's first encounter with a rat came in South City, behind his grandparents' house on Wyoming Avenue, in the early 1960s. The alley behind the house held rows of old chicken coops, and even as a child, Ritter had heard stories about rats back there.

"I was told that rats used to come up from under the coops and grab a sick or dying chicken every once in a while," he says. "Then one day I was back there and fell into a huge rat warren. I stepped on it, and my foot went a couple of feet underground. Later that evening, my grandfather saw a rat hole and used the old tried-and-true method of dealing with rats in the 1960s. He poured gasoline down the hole and soaked the rats and set it on fire. We don't urge people to do that anymore. There are safer and less illegal ways to treat a rat problem."

As a boy, Ritter, whose father worked for Ozark Airlines, wanted to be a pilot. But he ended up working at Maryville University, where dealing with rats and other pests was part of his job. He never intended to become a rat expert.

"My wife's generally pretty amused by it," Ritter says. "She calls me the Vermin Man; sometimes in the summer she calls me Mosquito Man. My friends just love to call me Vermin Man. They just love it to death. It is kind of fun, though, to go to a party, and when someone asks me what I do for a living I can say, 'I kill things.' One aspect of my job I like is that on stressful days I can just gather my guys and tell them, 'Go forth and kill.'"

Not everyone shares Ritter's bloodlust. Even though most rat experts are found in the pest-control industry, a few people have had positive experiences with rats and see them as no different from any other animal.

"Just because they're pesky to us doesn't mean they don't have their own world, their own lives, too," says Kathy Guillermo, a spokeswoman and writer for People for the Ethical Treatment of Animals. "They just do what they have to to survive."

During the late 1980s, Guillermo kept a brown rat she rescued from a local shelter in her office and, later, at her home in California. The rat, whom she named Angus, amazed her with his vibrant personality and affection during the four years she kept him. "Once Angus realized he wasn't going to be injured or hurt if he came out of the cage, he learned to come out, and he'd run to the edge of my desk or he'd stretch out on the top of my typewriter," Guillermo recalls.

Even when rats aren't as personable as Angus, Guillermo says, prevention, not extermination, is the answer. "People leave dog food out on the back patio or have large gaps under their garage door, then complain because they have rats. The way to deal with it is to stop it in the first place."

Ritter, on the other hand, has no compunction about killing rats. He may have the weight of history on his side: "They're a public-health concern. If you have a severe rat infestation and they're carrying the plague, you have a severe health issue. If you look at your history books, look at Europe in the fourteenth and fifteenth centuries. That's always in the back of your mind."

In their continuing efforts to keep the plague at bay, Ritter's nine vector-control employees last year conducted more than 2,000 inspections for rat complaints and treated nearly 600 sites.

Since the '70s, when St. Louis started using metal-and-plastic containers for garbage collection, rats haven't been a significant nuisance. But in a river town with high concentrations of restaurants and a sewer system with sections that date back to the mid-nineteenth century, rats will always be around.

"There are spots in certain areas of the city that we've been targeting for a number of years," Ritter says. "We'll always be treating them until the building is torn down or the sewer system is replaced. We can control it, but we'll never exterminate them completely."

Rats need three things to survive: food, water and shelter. "Any place you have all three of those things, you can have a rat population," says Greg Baumann, technical director of the National Pest Management Association in Dunn Loring, Virginia. "The types of food they eat are consistent with the types of food we eat. If there's an explosion in the rat population, it's one of two reasons: either a sanitation issue, which is true of a lot of pests, or there's a food source or a place to live."

The most effective way to treat a rat problem is to first exterminate the existing population -- with poison applied to the burrow or, in rare circumstances, traps -- and then to block access to food, water and shelter so that more rats don't move in.

"You can sometimes control harborage, you can definitely control food and you can definitely control water," Ritter says. "If you can control two of those factors, then you introduce poison bait so they'll eat it. Then you're in good shape."

Most thriving rat populations depend on the unwitting cooperation of people. In some cases, as in the North St. Louis neighborhood Ritter inspected in late March, sewer problems are the primary cause. But most often it's simple human oversight that brings rats.

"Most of the time, when people get them, there's a situation in the yard that's attracting them, or an old sewer system separation where they can get to food and fecal matter," Ritter says. He mentions an elderly woman a few years ago who fed birds in her back yard with a whole ham hock.

"Most people aren't aware they're doing it."

But the city's 150-year-old sewer system can be a problem even when people are careful about rats. The ancient pipes, some of them made of clay and brick, often separate, creating leaks and spills that quickly attract rats and other vermin.

"Some of [the pipes] have held up, to the surprise of today's engineers," says Ollie Dowell, director of public affairs for the Metropolitan St. Louis Sewer District. "The thing is they're just old. One of the problems, especially in the city, is that the combined sewers may break, and in that case you have a situation where what's supposed to be in the sewer gets in someone's basement or back yard."

In March, the MSD board removed a measure from ballots that, if approved by voters, would have allowed the agency to issue $500 million in bonds to pay for new sewer lines and sewer plants. The agency's board was replaced after state auditors smelled a rat in MSD's accounting practices. The new board withdrew the measure, but it may return. "We'll get it back on the ballot in November," Dowell says, "hopefully."

Rats, like human beings, can be found anywhere. They have no particular affection for the city. And, like people, many rats fled to the suburbs years ago. "They can survive anywhere humans survive," Baumann says.

Every summer, rat complaints seem to pop up in unexpected places. In September, residents of St. Ann complained to their City Council about rat sightings. The year before, people in St. John and Maplewood had similar problems. Unlike the city, St. Louis County's vector-control office doesn't treat rat infestations.

"We can't bait on private property, just public property," says Ellen Waters, public-information officer for the St. Louis County Health Department. In the county's municipalities and in St. Charles County, the police and health departments are usually willing to help people with rat infestations, but exterminators are generally the most effective -- if somewhat expensive -- way to get rid of rats in the suburbs.

Jeff Holper, who's run Holper's Pest & Animal Solutions for eighteen years, says rats and mice make up about a quarter of his business. Clayton and University City, especially around the Washington University campus, are particular problem areas for Holper. "There's a huge pocket of old sewers in Clayton, so they have a huge rat problem," Holper says.

"Then there are a lot of people who think they're feeding birds but they're just making the rats fat and happy. They have no idea what's underneath their bird feeder at night." When they find out, Holper says, it can be "a life-changing experience."

One of Holper's clients -- who asks that his name not be used -- had that kind of experience. A few years ago, the man and his wife were out on a Sunday afternoon. Their sixteen-year-old daughter and thirteen-year-old son were at their home in Clayton.

"We got a phone call. My daughter was screaming frantically," he says. "I thought an intruder was in the house or someone was injured. It sounded like an incredible crisis. She was crazy on the phone."

It took a few minutes to sort out what had happened. Their daughter had gone into the bathroom on the second floor of the house, lifted the toilet seat and stared straight into the eyes of a rat.

"I told my son to go upstairs and put the seat down," he says. "He said he wasn't going up there. My son and I hunt together, and he thinks of himself as a manly kind of guy. He would not go back inside to close the seat."

That was one of several episodes with rats the family experienced. A year earlier, the son had found a dead rat in a trap inside the shower stall. "I don't know if you've had the pleasure of seeing a rat in a trap," Holper's client says. "The snout gets caught, and it shoots blood everywhere. You're just walking calmly into the shower and see that, or getting ready to sit on the throne and run into one. My son wouldn't even go back in the bathroom. My daughter's in college now, but she doesn't use that toilet any more when she comes home."

Ritter has similar stories, such as the one about a nearly blind woman who thought she was feeding squirrels in her back yard -- they were rats -- and let them crawl in her lap. Or the St. Louis police officer who was ready to shoot a rat he had trapped in his bathroom. Or the 110-pound rottweiler, raised for illegal dog fights, backed up against a fence by a pack of five or six rats. Or the house with 200 rat burrows in the back yard.

Ritter doesn't like rats. Anyone who's spent twenty years killing them probably doesn't. Even after so much experience, he still finds them creepy. But his life has become inextricably intertwined with theirs, and he often finds himself trying to think like a rat.

"It's easy for me," he says. "I'm a bureaucrat."

He knows what rats do, where they do it and why -- almost as well as he knows himself. Although he thinks about rats a lot, he doesn't dream about them, keep them as pets or train them to do his bidding. He likes telling his stories, and he takes some satisfaction in being the city's go-to guy on vermin, but it's a job, not an obsession. He's proud of cleaning up the worst rat infestation he's ever seen, two years ago, at a grain elevator on the north end of Grand Boulevard, near the river. "It was a rat city -- let's put it that way," he says. It took him three months, but he cleared the rats out, and they haven't been a problem since.